Beaver Tips

[Rowdy]

Watch MP and RPM on takeoff. A couple of the machines I flew may not have been setup correctly in the governor or throttle linkages and would exceed takeoff specs. Overboosting is a quick way to put a lot of added strain and pooch an engine over time.

Each operator also wanted us to use a different set of power settings.. one wanted max continuous in climbs and then back to a low cruise of 27/17, another wanted to see 30/20 right after you broke water and 29/19 in cruise. Another wanted as low of a power setting as you could get in cruise. Plus each and every machine will have a slightly different "happy" spot. That goes for all aircraft engines. It might be a few rpm lower or higher or a couple inches or half an inch of MP than the factory settings. Those beautiful 985s are getting to be antique pieces these days.

I always found on longer trips that 28/18 worked best in one machine and another liked 26/1750. Things would just smoothen out, the pax would fall asleep from the drone and all would be well temp wise.

I love the ol' girl!! Dehavs are my favorite!!

[tzu]

As per bible 5.1.2(b)
- Serious detonation may be caused if the engine is run continuously on one magneto, with manifold pressure as high as 25 to 30 In.Hg.



Could someone possibly shed some light as to why detonation would occur with operation on one mag?

Wouldn't operating on one mag be less efficient on fuel burn, and as a result may lead to an over-rich mixture?

[xsbank]

What I know: detonation is the uncontrolled burn of the fuel charge in the cylinder, usually BTDC. Can cause serious engine damage. Overly-lean mixtures, cylinder head temps too hot, manifold pressure too high, ignition timed incorrectly etc.

WAG: on one magneto, perhaps the charge is not completely burned or the local temperatures are too high and when the next fuel charge is introduced it combusts spontaneously? Remember that above a certain throttle setting, (don't remember what that is - help me out here) excess fuel is introduced to keep the cylinder heads cool, perhaps it is this extra charge, compressed to a large degree by the supercharger, improperly controlled by the loss of half the ignition that causes the detonation?

The tetraethyl lead they used to add was to prevent some detonation and have a controlled flame front. That has been largely removed now. Also remember that the fuel is not supposed to ever 'explode' even at the correct time.

Rowdy, you have lots of "supercharger" experience, comments?

[tzu]

[tired of the ground]

Just for another WAG. Detonation can be caused by carbon buildups on the pistons that act like glow plugs and can cause ignition. I would imagine that one mag operation is less efficient and could lead to incomplete (rich) combustion and carbon buildups.

Worth what you paid for it.

[tzu]

Crosswind tips?

Climb flap... no flap... extra power..
Any other techniques by the seasoned drivers?

[phillyfan]

You can try playing with the flaps but the redline is there for a reason.

[tzu]

You can try playing with the flaps but the redline is there for a reason.

?

[phillyfan]

More power as in more then 36.5 in?

[adhc2]

As per Beaver manual Max takeoff power is 36.5" & 2300 rpm reduce as soon as possible to (max 1 min) Max continuous 33.5" and 2200 rpm. Further reduce numbers by 2% per 11C below standard ambient temp of 20 C .Max continuous is of course max and normal ops reduce to 30" .Some will fly heavy with just a small notch of flap to enable a lower nose attitude, never the less you may be using flap at above published limits in doing so. This may put additional load on flap system overtime leading to premature wear but I suspect not significantly. It may give you a little more speed and therefore better cooling on those hot and heavy days. just remember they will haul a serious load but when heavy it performs much more lethargicly and therefore exersize appropriate caution and diligence.

[mr.jinks]

do people actually set the throttle linkage up to stop at 36.5 on a standard day? ... every one i have seen will go way past if firewalled.

[angry inch]

No... That would really suck if you took off at sea level & went into a lake at 5000'...

[buck82]

Or even had a hot day at sea level...

[Wildernesspilot]

I fly the Beaver in open ocean conditions and although rarely see calm water I'm finding it hard to get a good glassy water configuration, any advice?

[Siddley Hawker]

70 mph with climb flap seems to ring a bell. You needed about 20 inches of MP, and that gave you around 300 fpm rate of descent. Try that and see if it works. When you get into ground effect the airplane will flatten itself out a little. It's been 40 years since I flew one, so I could be full of shite on that.

[cdnpilot77]

Can anyone post some tips on flying the mighty beav with wheel-skis

[Wildernesspilot]

Siddley Hawker thanks for that, I will try it tomorrow and let you know.

[Slats]

Can anyone post some tips on flying the mighty beav with wheel-skis

I found it even easier to fly on straight wheels than on floats, if that's possible. Not sure about skis though. Had a great deal of difficulty getting the tailwheel to caster (sp?) but assumed it was due to the specific aircraft and usually operating on slippery hard-packed snow conditions.

For glassy water, I never really changed my usual configuration at all, just used power as necessary and found it always worked beautifully. Always found the Beav easier to land glassy water than Cessnas.

The airplane is truly a dream to fly when operated within its limitations for its intended purpose.

[Rowdy]

What I know: detonation is the uncontrolled burn of the fuel charge in the cylinder, usually BTDC. Can cause serious engine damage. Overly-lean mixtures, cylinder head temps too hot, manifold pressure too high, ignition timed incorrectly etc.

WAG: on one magneto, perhaps the charge is not completely burned or the local temperatures are too high and when the next fuel charge is introduced it combusts spontaneously? Remember that above a certain throttle setting, (don't remember what that is - help me out here) excess fuel is introduced to keep the cylinder heads cool, perhaps it is this extra charge, compressed to a large degree by the supercharger, improperly controlled by the loss of half the ignition that causes the detonation?

The tetraethyl lead they used to add was to prevent some detonation and have a controlled flame front. That has been largely removed now. Also remember that the fuel is not supposed to ever 'explode' even at the correct time.

Rowdy, you have lots of "supercharger" experience, comments?

XS, you're pretty spot on there.. Look at where the plugs are situated.. they arent in a central location in the cylinder head. They are in fore and aft positions.. So you're right, getting an incomplete burn which could cause carbon buildup or perhaps some of the unburnt fuel to sit on or around a valve or imperfection in the case or casting or even on the piston crown and ignite during another incorrect time in the cycle. Now you're also going outside of the norm for the internal combustion engine and forcing compressed air and fuel into this cycle.. I know from experience at high boost levels that the single (factory) ignition on a couple of the turbo car motors I've run would actually run out of jam so to speak. You'd be blowing out that spark and not getting the correct ignition of the fuel.. I'll see if I can dig up some old pics of the burnt valves and lifted crown from such an experience.. Albeit that was a few seconds of detonation at high boost levels (30psi). Like the factory book notes.. I'm sure at the lower boost levels that a 985 is spinning in cruise wouldnt cause instantaneous damage, but prolonged running would build up carbon deposits on valves and the piston head/crown. And like tired of the ground said.. act like a glow plug and retain enough heat to cause ignition on the compression stroke. Now dont forget.. theres a lot more heat with all that forced air already..

The lead was (and still is in 100LL) there for more than just a reduction in detonation by increasing the octane rating. R+M/2. It was also there to aide in forming a seal (read buildup) on the valve seats as well. You'll remember that a lot of vehicles that used to run and were designed for leaded fuels needed to have hardened valve seats installed in the heads or be run with a lead additive. I'm not THAT knowledged on the internals of the 985.. but I'm guessing with it's STC approval for the use of Mogas and 80/87 that they already have hardened seats or they were added at some point. Any of the knowledgeable AME's care to comment on whats involved with the STC or if I'm way off base here?

[Siddley Hawker]

I can remember when we ran the small Pratts on 91/98. When that was phased out for 80/87 the power settings remained the same. One year we ran out of 80/87 on the coast and used 100/130 for the last few weeks of the ski season. I seem to recall that for every hour in cruise at 28 and 18 we were supposed to apply METO power for one minute. That really didn't amount to much because most of our hops were less than 30 minutes anyway.

Somebody asked about ski tips. I don't have much ski time on the Beaver, but I've flown both Federal and deHavilland skis. There's something to be said for both types. In soft snow the Federals are better because of the larger footprint. Downside is you are either full skis or full wheels. The deHavs you can select half and half to use a little brake if the conditions warrant. On skis, always do wheel landings with the tail low. The airplane is fairly stiff-legged in drifts, here again the Federals are better because the wheel sits on top of the ski and will absorb some of the impact. Stay out of slush with either type. Unless you're sporting the skis that Fecteau used on theirs. They hung Otter wheel replacement skis on their Beavers and could pretty near land on clear water as long as you had a decent place to park.

Wp, I hope you never got yourself into a peck of trouble with that glassy water procedure. Like I said, it's been awhile.